The growing consumption of water by human communities and agricultural activities requires the development of new sources of fresh water. One largely untapped source of fresh water is the water which exists in the air, in the form of water vapor. This water can be condensed from the air by bringing the temperature of a solid surface below the current dew point temperature, that is, the temperature at which humidity reaches 100 percent and the air is saturated with water vapor.
A number of businesses are currently providing systems to condense water out of the air, for both drinking and irrigation. These include, as examples, Element Four Technologies Inc. and Air Water International Corporation. In an exemplary system, air is forced through a condensing tube by means of a fan. In a conventional arrangement, the tube could be surrounded by refrigeration coils. The system may be activated to collect water when sub-dewpoint temperatures can be efficiently achieved, which typically occurs in the morning just before sunrise.
Notwithstanding the merits of prior art systems of the above type, such systems tend to be deficient in certain respects, especially when used for plant irrigation. For example, in scheduling the operation of a prior art condensing system to produce water for specified plants, the scheduling process typically does not take into account the energy efficiency of the condensation system, or the fact that a given plant can have different needs for water at different times, at different stages of plant growth. The scheduling process may also disregard the availability of water that was condensed previously and placed in storage, nor does it consider current soil moisture, or the use of forecasts that pertain to weather or plant evapotranspiration. Moreover, prior art systems typically do not make efficient use of available energy, and may fail to consider battery charge level, or the availability of battery recharging energy, in scheduling water condensation operations.
As a result of these shortcomings, efficiency in the operation of prior art condensation systems for plant irrigation can be significantly diminished.